Can a Tooth With Resorption Be Saved? What the Heithersay Classification Tells Us in 2026

Most dental problems announce themselves with pain. External cervical resorption (ECR) often doesn't. In this condition, the body's own cells begin dissolving a tooth from the outside — usually starting near the gumline, at the "neck" (cervical area) of the tooth — and it can progress for months or years before a patient notices anything more than a faint pink discoloration or a spot their dentist catches on a routine X-ray.

Once ECR is found, the decisive question is always the same: can this tooth be saved, or has the damage gone too far? A 2026 narrative review in the International Endodontic Journal (Rossi-Fedele and colleagues) tackled exactly that — examining how well two classification systems predict the outcome. The findings are genuinely useful for patients trying to understand their prognosis.

How resorption is classified

Two systems are commonly used to describe how far ECR has spread:

• The Heithersay classification (Classes I–IV), based on 2D X-rays, grades how deep the lesion has penetrated into the tooth and root.
• The Patel classification, a newer 3D system based on CBCT (cone-beam CT) scans, describes the lesion's height, spread around the tooth, and proximity to the root canal.

What the 2026 review found about prognosis

The review's central finding is clear and clinically important: the Heithersay class strongly tracks with prognosis. In plain terms, the smaller and shallower the lesion when it's caught, the better the odds of saving the tooth.

• Class I and II (small lesions confined to the crown area or reaching the coronal root) were associated with high survival and success rates — these teeth are frequently saved.
• Class III is a guarded, case-by-case zone.
• Class IV (extensive lesions spreading deep into the root) carried a poor prognosis — these teeth often cannot be saved.

The surprising finding about 3D scans

Here's the part that surprised many clinicians. CBCT scans are, without question, the best tool for diagnosing ECR and mapping its true extent — 2D X-rays consistently underestimate these lesions, and 3D imaging is the standard of care for planning treatment. The review does not dispute any of that.

But when it came specifically to predicting the outcome, the authors found there was not yet enough evidence to confirm that the Patel (CBCT) classification reliably predicts prognosis. The older, simpler Heithersay system currently has the stronger track record for forecasting whether a tooth can be saved.

This is an important nuance, not a contradiction: use CBCT to see the lesion accurately, and lean on the Heithersay class to discuss the odds — while research continues to validate the newer 3D system for prognosis.

Why early detection is everything

The single most powerful theme running through the evidence is timing. Because ECR is usually painless, it is often discovered late — and by Class IV, options narrow dramatically. Catching it at Class I or II can be the difference between a straightforward repair and losing the tooth.

That's why routine dental checkups and X-rays matter even when nothing hurts, and why any unexplained pink spot on a tooth deserves prompt evaluation. If your dentist mentions possible resorption, don't wait.

What treatment looks like

For treatable lesions, an endodontist can often remove the resorbing tissue and repair the defect with a biocompatible filling material, sometimes combined with root canal treatment — all performed under a surgical microscope with CBCT guidance. The right approach depends entirely on the lesion's location and class, which is precisely why an accurate diagnosis and honest prognosis conversation come first.

Dr. Jason Kung diagnoses and treats internal and external resorption using low-dose CBCT imaging and microsurgical repair at Silicon Valley Endodontics & Microsurgery. Learn more about tooth resorption diagnosis and treatment, or contact our office if resorption has been found on one of your teeth.